What happened
On 6 July 2021, a Robinson R44 helicopter, registration SP-CCC, departed from a private property near Mikołajki, Poland, for a recreational flight to Ułęż. The flight was carrying the pilot and two passengers. During the initial climb, the pilot attempted to adjust the cabin air due to high temperatures within the cockpit. In doing so, the pilot mistakenly pulled the mixture control knob instead of the cabin air knob, which leaned the fuel-air mixture and caused the engine to shut down.
Upon realizing the engine had failed, the pilot immediately attempted to reset the knob, but the main rotor RPM began to drop rapidly. The pilot initiated an autorotation procedure; however, due to the low altitude (approximately 40 meters AGL) and low airspeed, the rotor RPM could not be recovered. Just before impact, the pilot increased the collective angle of attack to slow the descent, but the helicopter ultimately ditched hard into Tałty Lake. The impact caused the pilot to lose consciousness temporarily, though all three occupants eventually surfaced and were rescued by a private motorboat.
The investigation
The PKBWL investigation focused on the cockpit configuration and the sequence of events leading to the engine failure. Investigators examined the aircraft's maintenance records, which were found to be in order, and verified that the aircraft's weight and center of gravity were within limits. A technical analysis of the wreckage revealed that the mixture control knob lacked its protective guard at the time of the accident, a component that may have been lost during the impact or recovery.
Furthermore, the investigation compared the cockpit layout of the SP-CCC with other Robinson R44 models. It was determined that the pilot had previously operated R44 II models, where the location of the cabin air knob and the mixture control knob differed from the model involved in the accident. This discrepancy in control placement contributed to the pilot's error.
Findings
- The primary cause of the accident was pilot error resulting in the engine shutdown after takeoff.
- High ambient and cabin temperatures prompted the pilot's attempt to adjust the air supply.
- The pilot's previous experience with different helicopter models led to incorrect muscle memory regarding knob locations.
- Time pressure, driven by the need to complete the flight before airspace restrictions took effect, contributed to the pilot's haste.
- The low altitude and airspeed at the time of the engine failure prevented the execution of a successful full autorotation.
- All three occupants sustained serious injuries requiring hospitalization.